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Efficiency - Built-in power losses

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Posted by James Baber on September 28, 2004, 6:48 pm
 
I see a lot of neat things here.  I am a great fan of solar PV, and I have been
successful in using it. Wind is good if location is appropriate.  Small hydro
can be good for some, and I would like to live where it was.

What is common to everyone, 'efficiency'!

By now we have all started using CFL (compact fluorescent lamps, you know those
twisty things) lights.  They use much less power (Watts) for the amount of light
they produce, but even so they are very inefficient and waste 25-50% of the
power they do use if they are measured for their powerfactor losses.

Powerfactor losses account for 15% of all the energy paid for by the nations
utilities customers on the average nationally.  This can be proved by these
utilities actually planning their capacity requirements on this figure.  In fact
if you are a major industrial or commercial user the utilities will charge you
extra if you don't correct your own powerfactor.  As far as the small consumer
is concerned, the utilities have historically wanted you to buy more power, so
they didn't tell you about these losses you do have to pay for.

When I built my solar PV system, I went all through my home looking for things
to do to reduce my needs and make the very expensive initial cost of the PV
system as small as possible.  This took about 1 year to complete and the I sized
and designed my solar system.  After I bought the hardware for the system, I was
reading the inverter manuals.. (Really I do read instruction manuals as strange
as that may be to some) .. and I tripped over the statement that the inverters
had a powerfactor of 1.0

I dug into my mental archives over powerfactor, since I knew I had NOT
considered powerfactor in my planning.  It had been in 1962 when I had last
considered Powerfactor, but at that time I was designing power supplies for
NCR's mainframe computers.  As I recalled we were able save a significant
savings in the AC power requirements for those mainframe computers by correcting
the powerfactor losses from the power supply transformers with 60 cycle tuned
capacitors.

I proceeded with my solar PV, figuring the losses in my home were not
significant, but I started looking for a powerfactor meter, and I eventually
bought one that had a wattmeter and would record its readings for input into my
computer.  I didn't tell my wife how much, just that I was ($50.00).

It is a neat tool, and like most techie types would, I started measuring things.
The refrigerator, water heater, stove top, ovens, and finally the 240 input from
the meter to the house.

OUCH, the powerfactor was a miserable 0.81, with my PV solar turned off.  It
should ideally be 1.0 and this meant that in the year before I put in the PV I
had wasted 4458 kWh of the 23,464 kWh I had paid $,446.00 for in that prior
year.  This meant I had lost at least $44.00 to the bad powerfactor.

The 4458 kWh used to offset the powerfactor loss would also work against
whatever power I generated myself as well as any power I was planning to draw
from the grid, so I decided to find some compensating capacitors to install to
correct the bad powerfactor.  It was not easy but I did, it cost $50.00, but it
  easily has paid for itself.

The only problem with fixing this powerfactor loss, I had sized my PV system so
that when my utility and I settle at the end of each year I had planed to pay
about  $00.00 on my bill (annually) to keep from giving them any credit.  Last
year that's about where we finished, but this year it looks like I'll have at
least a $00.00 credit on my account that they just get to keep.  Oh well I
won't have to pay anything!

--

Jim Baber

(see my 10kW grid tied solar system at "www.baber.org")

1350 W Mesa Ave.
Fresno CA, 93711
(559) 435-9068
(559) 905-2204 cell

Email jim@NOJUNKbaber.org

Posted by Jeff Wisnia on September 28, 2004, 11:16 pm
 
James Baber wrote:

<snipped>

Why am I smelling the sweet aroma of spam here guys?

Seems like Mr. Baber may be another sharp cookie trying to sell us Girl
Scouts, only in this case it's power factor correction systems, as
evidenced by the "Email an Order" button on his "KVAR page."

I don't disagree with the potential money saving advantages of
correcting the power factor of your home's electrical usage, but it
would have been classier if Mr. Baber came right out and told us he had
something to sell us.

Power factor correction using capacitors has been around in industrial
applications for as long as I can remember. This is the first time I've
seen any advertisement for a home unit. Why is that? And, does a unit at
that price level have the ability to adjust itself automatically so that
it doesn't overcompensate when the AC and other motor loads are off and
the remaining loads are already at or near unity power factor?

I'd be interested in learning what his entire PV system cost, for all
the equipment and a fair price for having it installed by contractors.
It would be fun to calculate the payback time for that sort of
installation, including factoring in the time value of money and
maintenance.

I didn't see any mention of energy storage as part of the PV system, so
I presume that it will only make ac power when the sun shines. It does
make sense to me that PV should be quite helpful for reducing the peak
loads caused by AC systems which obviously work harder during the day
than they do at night.

Is it presently cheaper for power companies to generate electricity with
PV systems? I don't know the answer, but I'd like to learn.

Just my .02,

Jeff

--
My name is Jeff Wisnia and I approved this message....

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"

Posted by Old Fangled on September 28, 2004, 11:29 pm
 vQ@conversent.net:


They aren't new -- even Consumer Reports looked at one.  They don't save
you any money at all, since the power meter at your house measures true RMS
power and is unaffected by your power factor.  It's only when you are a
large industrial consumer do you get a meter that measures power factor as
well as true power.

Posted by James Baber on September 29, 2004, 4:58 pm
 Jim replies to Jeff:
I have not sold ANY KVAR units, I have referred 1 party to my vendor.  I have
thought about selling them, but have not inventoried any.  At this point I still
am evaluating them as a major part of my entire program, but, they do appear
effective at this point.


Jeff Wisnia wrote:

Note, I didn't have an order form, or any specific way to order on my own site,
just an invitation to email me for more information.  Again I just referred the
1 person I have corresponded with to my vendor, and do not know if that person
has bought a unit.

I don't understand why nobody has promoted any other similar product, except
that capacitors of a size suitable for a whole house's loads are large and of a
size that they require separate housing from the normal power distribution box.
This box should be at least a NEMA 4 box and needs to be weatherproof.

Also the installation of any electrical equipment attached directly to the power
service should be installed by a licensed electrician, and it was my experience
that it was difficult to find one willing to mess with a 30 minute job that was
unfamiliar to them.  The one that I did use for my own KVAR unit, was willing
because I had him also installing time clocks on 2 electric (220V) water
heaters.  He was also new in the area, and was trying to build his business.

Another point, the whole concept of powerfactor is so unfamiliar to 95% of the
populace that anyone promoting the idea of correcting it, must be trying to con
them, when obviously their power is OK now.

This large part of the population doesn't understand the difference between AC
and DC load reactance's (resistance's), and frankly they don't care and they
don't want to know as long as the lights come on when they flip the switch.


I have calculated it (payback) at about 5.5 years considering my loan costs and
my total costs and the actual performance of the first 15 months of operation. I
would be willing to go into in detail, but I've done that several times, all non
design work has been done by my contractors as I am severely limited by my
emphysema.
The major points:
COSTS
   (1,100) carpentry work (False wall, inverter cabinetry, minor roof mod.)
($1,000) primary PV system (panels, inverters, & installation cost.
    ($50) cost KVAR unit & 2 water heater timers incl'd.
    ($77) cost of converting to Time Of Use metering on grid for the meter.
    ($00) cost of new 1st Mortgage refinance that raised mortg. bal by 40,000
              Payment went up by $4.00, but will be paid off 3 years earlier.
              No change to tax assessment allowed under California Law.
OFFSET INCOME or INTEREST
  $9,980  Rebate from the California rebate @ $.00 per their wattage calcs.
   $,300  One time 15% (net$) State income tax credit on our 2004 income tax.
   $,000  Estimated annual utility savings (1st 6 without KVAR or TOU)
           1st 12 months actual = $50.30  the prior 12 months = $,446.00
           next 3 months actual = (165.67) from the utility's statement HOT!
   $,800  estimated savings in Federal & State income taxes (larger interest
           deductions because of new loan having larger early ded'n than orig.)

I don't personally "store" any power. I am on Net grid metering, so any power I
do not immediately use is exported directly to the grid, and I do draw power
back at night and whenever I need more power from the grid.  So in effect I do
use the grid like a battery, but it only costs me a $.37/mo. service charge,
unless I use more than I produce. (MUCH cheaper than batteries) Under this net
grid plan I will lose any outstanding $ credit (earned at the sam kWh rate as I
  would have to pay) I might have at the annual settlement.


Interestingly enough I am making an average 28.94 kW out of the average 49.68 kW
that I generate daily during the noon to 6 PM peak usage hours. So this really
helps my utility.

Jim Baber

(see my 10kW grid tied solar system at "www.baber.org")

1350 W Mesa Ave.
Fresno CA, 93711
(559) 435-9068
(559) 905-2204 cell

Email jim@NOJUNKbaber.org

Posted by Jeff Wisnia on September 29, 2004, 6:54 pm
 James Baber wrote:

I may have come on a bit too strong James, but when I saw you'd cross
posted to a lot of other newsgroups and then noted that you hadn't
posted to this group before (at least in the last month) I "smelled SPAM".

And you do/did have an "Email an Order" button on your "KVAR page", but
I didn't bother to click on it.

All that said, a lot of folks have responded to this thread to state
that "whole house" power factor correction will have no direct effect on
the typical homeowner's power cost, because the usual residential meters
measure RMS power, which do not measure or record anything concerning
the power factor of the load they are metering.

You may well have a more sophisticated metering setup from PG&E, where
your two homes' overall power factor may in fact directly affect your
bill. That wouldn't suprise me given that you have a system where you
can in effect "run the meter backwards" when you are putting power back
on the grid from your PV system.

If you know, or can find out from PG&E whether your metering takes power
factor into effect I'd like to learn.

Thanks for all the other info.

Cheers,

Jeff


--
My name is Jeff Wisnia and I approved this message....

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"

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